04 The Chromosome Theory And Linkage

2.

The last names of the two scientists who proposed the Chromosome Theory in 1902 are Boveri and _______.

Explanation
The Chromosome Theory, proposed in 1902, was put forward by two scientists: Boveri and Sutton. Therefore, the missing last name is Sutton.

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3.

Sutton and Boveri noticed this correlation between chromosome behavior and gene behavior:

Chromosomes and genes both occur in pairs.
Pair of chromosomes and pairs of genes both separate during gamete formation.
The separation of chromosome pairs and of gene pairs are both independent.
All of the above.
None of the above.

Correct Answer

A. All of the above.

Explanation

Sutton and Boveri noticed that there is a correlation between chromosome behavior and gene behavior. Both chromosomes and genes occur in pairs, and during gamete formation, both pairs of chromosomes and pairs of genes separate. Additionally, the separation of chromosome pairs and gene pairs is independent, meaning that the separation of one pair does not affect the separation of the other pair. Therefore, all of the statements mentioned above are correct.

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4.

A white-eyed Drosophila male receive its white-eye gene from its ________.

Correct Answer
mother
female parent
mom
mommy

Explanation
The correct answer is "mother" or "female parent" because in Drosophila, the white-eye gene is located on the X chromosome. Since males inherit their X chromosome from their mother, the white-eyed Drosophila male would receive the white-eye gene from its mother. The terms "mom" and "mommy" are informal ways of referring to the mother or female parent.

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5.

A Drosophila female that is heterozygous for the white-eye gene is crossed with a white-eyed male. What percent of the progeny (male and female) will be white eyed? ___%

Correct Answer
50

Explanation
When a Drosophila female that is heterozygous for the white-eye gene is crossed with a white-eyed male, the white-eye gene is dominant. This means that all the offspring will inherit the white-eye gene from the heterozygous female, resulting in 100% of the progeny being heterozygous for the white-eye gene. Since white eye is a recessive trait, only individuals that are homozygous for the white-eye gene will exhibit this trait. Therefore, 50% of the progeny will be white-eyed.

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1

6.

A homozygous dominant plant for three genes (A, B, C) was crossed with a homozygous recessive plant for these genes. The F1 generation plants were then test crossed with homozygous recessive plants. The phenotypes and number of plants of the next generation are shown below. ABC 390 ABc 97 AbC 12 Abc 2 aBC 3 aBc 13 abC 98 abc 385 Total 1000 The correct gene order is _______ (use all capital letters).

Correct Answer
BAC
CAB

Explanation
The correct gene order can be determined by analyzing the phenotypes and number of plants in the next generation. By comparing the phenotypes of the F1 generation with the phenotypes of the next generation, we can determine the gene order. In this case, the F1 generation had the genotype ABC, which resulted in the phenotypes ABC, ABc, AbC, and Abc in the next generation. By comparing these phenotypes with the given data, we can see that the genotype BAC corresponds to the phenotype ABC, and the genotype CAB corresponds to the phenotypes ABc, AbC, and Abc. Therefore, the correct gene order is BAC, CAB.

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7.

The progeny of the cross AaBb x aabb are: AaBb = 45; Aabb = 5; aaBb = 5; aabb = 45. These two gene are:

On different chromosome pairs
5 cM apart.
10 cM apart.
45 cM apart.
90 cM apart.

Correct Answer

A. 10 cM apart.

Explanation

The progeny of the cross AaBb x aabb show a 1:1:1:1 ratio, indicating that the two gene pairs Aa and Bb are assorting independently. This means that they are located on different chromosome pairs. The distance between two genes on a chromosome is measured in centimorgans (cM). Since the progeny show equal numbers of AaBb and aabb, and AaBb and aabb are the two combinations that result from a recombination event between the two gene pairs, it can be inferred that the two gene pairs are 10 cM apart on the chromosome.

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8.

A somatic cell hybridization experiment was performed and three hybrid cell lines were produced (23, 34, and 41). In each line, the chart shows which human chromosomes remained. The far right of the table shows + if the gene product of gene A, B, and C is present in the cells. The gene for B is on chromosome number ________.

Correct Answer
3

Explanation
In the given experiment, three hybrid cell lines (23, 34, and 41) were produced, and the chart shows which human chromosomes remained in each line. The far right of the table indicates whether the gene product of gene A, B, and C is present in the cells, with a "+" sign indicating presence. Since the answer is "3," it suggests that the gene for B is located on chromosome number 3.

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9.

A _______ score is used to calculate linkage from pedigrees.

Correct Answer
LOD

Explanation
The LOD score, or logarithm of the odds score, is a statistical measure used in genetics to determine the likelihood of linkage between genes based on pedigree analysis. It compares the probability of the observed pedigree data occurring under the assumption of linkage to the probability of the same data occurring under the assumption of no linkage. A LOD score greater than 3 is generally considered significant evidence for linkage, while a score less than -2 suggests evidence against linkage.

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04 The Chromosome Theory And Linkage

Chromosomes were discovered by: (I don't think we didn't cover this one this year, 2010)

Quiz Preview

The last names of the two scientists who proposed the Chromosome Theory in 1902 are Boveri and _______.

Sutton and Boveri noticed this correlation between chromosome behavior and gene behavior:

A white-eyed Drosophila male receive its white-eye gene from its ________.

A Drosophila female that is heterozygous for the white-eye gene is crossed with a white-eyed male. What percent of the progeny (male and female) will be white eyed? ___%

The progeny of the cross AaBb x aabb are: AaBb = 45; Aabb = 5; aaBb = 5; aabb = 45. These two gene are:

A _______ score is used to calculate linkage from pedigrees.